linux-kernel - Re: [PATCH v6 3/3] KVM: trace kvm_halt_poll

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Date:	Wed, 2 Sep 2015 11:09:56 -0700
From:	David Matlack <dmatlack@...gle.com>
To:	Wanpeng Li <wanpeng.li@...mail.com>
Cc:	Paolo Bonzini <pbonzini@...hat.com>,
	kvm list <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 3/3] KVM: trace kvm_halt_poll_ns grow/shrink

On Wed, Sep 2, 2015 at 12:42 AM, Wanpeng Li <wanpeng.li@...mail.com> wrote:
> Tracepoint for dynamic halt_pool_ns, fired on every potential change.
>
> Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
> ---
>  include/trace/events/kvm.h | 30 ++++++++++++++++++++++++++++++
>  virt/kvm/kvm_main.c        |  8 ++++++--
>  2 files changed, 36 insertions(+), 2 deletions(-)
>
> diff --git a/include/trace/events/kvm.h b/include/trace/events/kvm.h
> index a44062d..75ddf80 100644
> --- a/include/trace/events/kvm.h
> +++ b/include/trace/events/kvm.h
> @@ -356,6 +356,36 @@ TRACE_EVENT(
>                   __entry->address)
>  );
>
> +TRACE_EVENT(kvm_halt_poll_ns,
> +       TP_PROTO(bool grow, unsigned int vcpu_id, int new, int old),
> +       TP_ARGS(grow, vcpu_id, new, old),
> +
> +       TP_STRUCT__entry(
> +               __field(bool, grow)
> +               __field(unsigned int, vcpu_id)
> +               __field(int, new)
> +               __field(int, old)
> +       ),
> +
> +       TP_fast_assign(
> +               __entry->grow           = grow;
> +               __entry->vcpu_id        = vcpu_id;
> +               __entry->new            = new;
> +               __entry->old            = old;
> +       ),
> +
> +       TP_printk("vcpu %u: halt_pool_ns %d (%s %d)",

s/pool/poll/

> +                       __entry->vcpu_id,
> +                       __entry->new,
> +                       __entry->grow ? "grow" : "shrink",
> +                       __entry->old)
> +);
> +
> +#define trace_kvm_halt_poll_ns_grow(vcpu_id, new, old) \
> +       trace_kvm_halt_poll_ns(true, vcpu_id, new, old)
> +#define trace_kvm_halt_poll_ns_shrink(vcpu_id, new, old) \
> +       trace_kvm_halt_poll_ns(false, vcpu_id, new, old)
> +
>  #endif
>
>  #endif /* _TRACE_KVM_MAIN_H */
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 3cff02f..fee339e 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1918,8 +1918,9 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_mark_page_dirty);
>
>  static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
>  {
> -       int val = vcpu->halt_poll_ns;
> +       int old, val;
>
> +       old = val = vcpu->halt_poll_ns;
>         /* 10us base */
>         if (val == 0 && halt_poll_ns_grow)
>                 val = 10000;
> @@ -1927,18 +1928,21 @@ static void grow_halt_poll_ns(struct kvm_vcpu *vcpu)
>                 val *= halt_poll_ns_grow;
>
>         vcpu->halt_poll_ns = val;
> +       trace_kvm_halt_poll_ns_grow(vcpu->vcpu_id, val, old);
>  }
>
>  static void shrink_halt_poll_ns(struct kvm_vcpu *vcpu)
>  {
> -       int val = vcpu->halt_poll_ns;
> +       int old, val;
>
> +       old = val = vcpu->halt_poll_ns;
>         if (halt_poll_ns_shrink == 0)
>                 val = 0;
>         else
>                 val /= halt_poll_ns_shrink;
>
>         vcpu->halt_poll_ns = val;
> +       trace_kvm_halt_poll_ns_shrink(vcpu->vcpu_id, val, old);
>  }
>
>  static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
> --
> 1.9.1
>
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